NEW HAVEN -- Nicholas Longrich isn't a home wrecker, but he recently had occasion to break up a family of dinosaurs.

It seems there had been some controversy over the dinosaur Triceratops, a large, horned animal that roamed the western part of North America roughly 65 million years ago. Paleontologists in Montana had published findings in 2010, saying that Triceratops was merely a younger version of another horned dinosaur, Torosaurus.

But Longrich and other Yale University paleontologists say they've proven otherwise. Their year-long study, recently published in the journal PLoS ONE, concludes that Triceratops is a separate animal from Torosaurus - something scientists had believed prior to the Montana study.

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"We had a lot of evidence going into this, and it became more and more clear as we went along," explains Longrich, a postdoctoral fellow in Yale's department of geology and geophysics.

Triceratops was a four-legged creature thought to be nearly 10 feet tall and 26 to 30 feet long. Its name means "three-horned face," and one of its distinct features was a curved, broad piece of bone called a frill.

Paleontologists have discovered about 100 Triceratops skulls, according to Daniel Field, a Yale graduate student who worked with Longrich on the study. Some of the most scientifically significant skulls are part of the collection at the Yale Peabody Museum of Natural History.

Longrich and Field took measurements and collected data on about 35 Triceratops and Torosaurus skulls, including visits to see specimens in Philadelphia and Washington, D.C.

The fossil record, they say, indicates there are mature specimens of Triceratops and immature specimens of Torosaurus, as well as physical differences in the frill between the two animals. In addition, the Yale paleontologists found no examples of intermediate fossils showing how Triceratops' appearance might change to look more like a Torosaurus.

"We're pretty confident in our conclusions," Field says. "It gives us a better idea of how diverse the dinosaur community was in North America. It looks like rather than only one large, horned dinosaur species in North America at that time, we had two."

Longrich is quick to point out that the idea of one dinosaur species changing its physical appearance over time is "not so far-fetched. You can get some major changes. But you'd see a growth trajectory. You'd see intermediate steps."

One of the challenges in paleontology going forward will be finding a better way to gauge the amount of physical variation within a species, Longrich adds. Such variation becomes obvious after you've viewed enough dinosaur skulls.

"They're like snowflakes," Longrich says. "Every single one is different."